Aerial turbojet engine igniter driving circuit

Abstract

The utility model discloses an aviation turbojet engine igniter drive circuit, relates to igniter drive circuit technical field, the circuit includes: PMOS transistor, resistor R4 and resistor RL, PMOS transistor source electrode forms direct current power supply input end, PMOS transistor source electrode and grid electrode respectively connect the resistor R4 both ends, resistor RL one end connects PMOS transistor drain electrode, resistor RL other end ground, the resistor RL other end ground, the resistor RL other end ground, the resistor RL other end ground. The MCU control circuit and the ignition power driving circuit are connected with the PMOS tube, and the MCU control circuit is connected with a control signal input end; the ignition power driving circuit comprises a power supply short-circuit protection circuit, a grid protection circuit, a Vgs overvoltage protection circuit and a Vds overvoltage protection circuit. Aiming at a conventional ignition control drive circuit, the control circuit is optimized and designed again, and potential safety hazards existing in the ignition controller drive circuit are eliminated; and the reliability and the stability of the whole ignition control drive circuit are improved.

Description

Technical Field

[0001] This utility model relates to the field of ignition drive circuit technology, and more specifically, it relates to an ignition drive circuit for an aircraft turbojet engine. Background Technology

[0002] With the rapid development of aerospace technology, micro turbojet engines are also developing very rapidly. Compared with conventional turbojet engines, they have been greatly simplified in terms of structure, weight, and cost. Turbojet engines typically use either electric heating or electric spark plugs for ignition. Regardless of the method used, a highly reliable drive circuit is essential. Conventional turbojet engine ignition control drive circuits typically employ MOSFET-based electronic switch control, as shown in the schematic diagram below. Figure 1 As shown; however, in actual engine ignition device applications, Figure 1 The driving circuit shown often has significant shortcomings in terms of safety, reliability, and maintainability:

[0003] 1. In terms of safety, the defect of this circuit is that it lacks safety protection measures. Because there are no protective measures, the external ignition device will ignite directly, causing the engine to misfire.

[0004] 2. In terms of circuit reliability, this circuit design has high requirements for the quality and reliability of electronic components and external igniters. If any electronic component is damaged, the circuit will not work properly.

[0005] 3. In terms of maintainability, since there are no redundant protection measures designed, the controller cannot be repaired once it is damaged. Utility Model Content

[0006] The purpose of this invention is to provide an ignition drive circuit for a turbojet engine. Compared with conventional ignition control drive circuits, the control circuit is redesigned and optimized to eliminate the safety hazards of existing ignition controller drive circuits and improve the reliability and stability of the entire ignition control drive circuit.

[0007] The above-mentioned technical objective of this utility model is achieved through the following technical solution:

[0008] This application provides an ignition drive circuit for an aero-engine turbojet engine, including a PMOS transistor, resistor R4, and resistor RL. The source of the PMOS transistor forms a DC power input terminal, and the gate of the PMOS transistor forms a control signal input terminal. The source and gate of the PMOS transistor are respectively connected to the two ends of resistor R4. One end of resistor RL is connected to the drain of the PMOS transistor, and the other end of resistor RL is grounded. The circuit also includes an MCU control circuit and an ignition power drive circuit connected to the PMOS transistor, and the MCU control circuit is connected to the control signal input terminal. The ignition power drive circuit includes a power supply short-circuit protection circuit, a gate protection circuit, a Vgs overvoltage protection circuit, and a Vds overvoltage protection circuit.

[0009] Based on the above technical solution, the present invention can be further improved as follows.

[0010] Furthermore, the aforementioned MCU control circuit includes an optocoupler driver, resistor R9, and resistor R1, wherein:

[0011] The 02 pin of the optocoupler driver is connected to the control signal input terminal. The A pin and K pin of the optocoupler driver are connected to one end of resistor R1 and one end of resistor R9, respectively. The other ends of resistor R1 and the other ends of resistor R9 are connected to form the power supply input terminal. The K pin of the optocoupler driver forms a new control signal input terminal.

[0012] The beneficial effects of adopting the above-mentioned further solution are: the MCU control circuit is based on an isolated optocoupler drive output circuit, which realizes complete electrical isolation between the MCU end and the MOSFET power output end. This control circuit has extremely strong anti-electromagnetic interference capability, and can also realize level conversion. When the new control signal input end is low level, the optocoupler reaches the rated working condition, making the other end of the optocoupler conduct.

[0013] Furthermore, the aforementioned MCU control circuit also includes a resistor R7, one end of which is connected to pin 01 of the optocoupler driver, and the other end of which is grounded.

[0014] Furthermore, the aforementioned power supply short-circuit protection circuit includes a resettable fuse F connected to the PMOS transistor. One end of the resettable fuse F is connected to the source of the PMOS transistor, and the other end of the resettable fuse F forms a new DC power input terminal.

[0015] The beneficial effects of adopting the above-mentioned further solution are as follows: By adding a self-resetting fuse at the power input terminal, when the MOSFET or external ignition device is abnormally damaged and short-circuited, the current increases to the fuse's melting current. The fuse will then melt due to overheating, thus breaking the circuit and preventing accidental sparking. When the current electronic devices return to normal, the fuse current returns to normal, and the circuit works normally. This circuit can provide safety protection when the MOSFET or ignition device is damaged, and the ignition device will not experience accidental sparking.

[0016] Furthermore, the aforementioned gate protection circuit includes a resistor R10 that is connected to the PMOS transistor. One end of the resistor R10 is connected to the gate of the PMOS transistor, and the other end of the resistor R10 is connected to pin 02 of the optocoupler driver.

[0017] The advantages of adopting the above-mentioned further solution are: avoiding the situation where the gate of the PMOS transistor is directly driven by the power transistor, which would cause the driven power transistor to turn on and off rapidly, but may cause voltage oscillation between the drain and source of the power transistor, or may cause the power transistor to suffer from excessive di / dt, resulting in false turn-on.

[0018] Furthermore, the resistance of the aforementioned resistor R10 is 10 ohms.

[0019] Furthermore, the aforementioned resistor R10 is also connected in parallel with diode D2. The input terminal of diode D2 is connected to the gate of the PMOS transistor, and the output terminal of diode D2 is connected to pin 02 of the optocoupler driver.

[0020] The beneficial effect of adopting the above-mentioned further solution is that the parallel diode D2 can discharge the gate at the falling edge of the pulse, enabling the field-effect transistor to be turned off quickly and reducing power consumption.

[0021] Furthermore, the aforementioned Vgs overvoltage protection circuit includes a diode D1 that is connected to the PMOS transistor. The diode D1 is located between the gate of the PMOS transistor and the resistor R4. The input terminal of the diode D1 is connected to the gate of the PMOS transistor, and the output terminal of the diode D1 is connected to one end of the resistor R4.

[0022] The beneficial effect of adopting the above-mentioned further solution is that a Zener diode (diode D1) is connected in parallel with the gate of the PMOS transistor to limit the gate voltage below the Zener diode's voltage value, thus protecting the PMOS transistor from being broken down.

[0023] Furthermore, the aforementioned Vds overvoltage protection circuit includes a diode D3 and an RC snubber circuit, with the diode D3 connected in parallel with the RC snubber circuit. The input terminal of the diode D3 is connected to the drain of the PMOS transistor, and the output terminal of the diode D3 is connected to the source of the PMOS transistor.

[0024] The advantage of adopting the above-mentioned further solution is that the MOSFET can be avoided by using diode D3 and RC snubber circuit.

[0025] Furthermore, the aforementioned RC buffer circuit includes a resistor R11 and a capacitor C1 connected to each other. The other end of the resistor R11 is connected to the drain of the PMOS transistor, and the other end of the capacitor C1 is connected to the source of the PMOS transistor.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] In this application, the MCU control circuit is based on an isolated optocoupler drive output circuit, achieving complete electrical isolation between the MCU and the MOSFET power output. This control circuit has extremely strong anti-electromagnetic interference capabilities and also achieves level conversion. A self-resetting fuse is added to the power input terminal. When the MOSFET or external ignition device is abnormally damaged and short-circuited, the current increases to the fuse's melting current. The fuse will then melt due to overheating, breaking the circuit and preventing accidental sparking. When the current electronic devices return to normal, the fuse current returns to normal, and the circuit operates normally. This circuit provides safety protection when the MOSFET or ignition device is damaged, preventing accidental sparking.

[0028] In this application, the added resistor R10 can prevent the PMOS transistor from being driven by the power transistor to turn on and off rapidly if the gate is directly driven. However, this may cause voltage oscillation between the drain and source of the power transistor, or the power transistor may be subjected to excessive di / dt, causing false turn-on. The diode D2 connected in parallel with the resistor R10 can discharge the gate at the falling edge of the pulse, so that the field-effect transistor can be turned off quickly and reduce power consumption.

[0029] In this application, a Zener diode (D1) is connected in parallel with the gate of the PMOS transistor to limit the gate voltage below the Zener diode's voltage regulation value, thus protecting the PMOS transistor from breakdown; at the same time, the diode D3 and the RC snubber circuit can prevent damage to the MOS transistor. Attached Figure Description

[0030] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0031] Figure 1 This is an ignition drive circuit for a conventional small turbojet engine.

[0032] Figure 2 This is an overall block diagram of the ignition drive circuit for a small turbojet engine in an embodiment of this utility model.

[0033] Figure 3 This is a schematic diagram of the connection of the igniter drive circuit in an embodiment of this utility model;

[0034] Figure 4 This is a waveform comparison diagram of the PMOS transistor gate drive before (left) and after (right) optimization in the embodiments of this utility model. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0037] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0038] In the description of the embodiments of this utility model, it should be noted that if terms such as "upper", "lower", "left", "right", "vertical", "horizontal", "inner", and "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the utility model product is usually placed in during use, they are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0039] Furthermore, the use of terms such as "horizontal," "vertical," and "sag" does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0040] In the description of the embodiments of this utility model, "a plurality of" means at least two.

[0041] In the description of the embodiments of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0042] Example:

[0043] For conventional ignition control drive circuits, the control circuit design is re-optimized to eliminate potential safety hazards in the ignition controller drive circuit; the reliability and stability of the entire ignition control drive circuit are improved. This embodiment provides an ignition drive circuit for an aero-engine turbojet engine, including a PMOS transistor, resistor R4, and resistor RL, as shown below. Figure 3 As shown, the source of the PMOS transistor forms the DC power input terminal, and the gate forms the control signal input terminal. The source and gate of the PMOS transistor are connected to the two ends of resistor R4, respectively. One end of resistor RL is connected to the drain of the PMOS transistor, and the other end of resistor RL is grounded. Figure 2 As shown, it also includes an MCU control circuit and an ignition power drive circuit connected to the PMOS transistor, and the MCU control circuit is connected to the control signal input terminal; wherein, the ignition power drive circuit includes a power supply short circuit protection circuit, a gate protection circuit, a Vgs overvoltage protection circuit and a Vds overvoltage protection circuit.

[0044] The MCU control circuit is based on an isolated optocoupler drive output circuit, achieving complete electrical isolation between the MCU and the MOSFET power output. This type of control circuit has extremely strong electromagnetic interference resistance and can also perform level conversion, such as... Figure 3 As shown, when the IO port outputs a low level, the optocoupler reaches its rated operating condition, causing the other end of the optocoupler to conduct.

[0045] Optionally, the above MCU control circuit includes an optocoupler driver, resistor R9, and resistor R1, wherein:

[0046] The 02 pin of the optocoupler driver is connected to the control signal input terminal. The A pin and K pin of the optocoupler driver are connected to one end of resistor R1 and one end of resistor R9, respectively. The other ends of resistor R1 and R9 are connected to form the power supply input terminal. The K pin of the optocoupler driver forms a new control signal input terminal. The MCU control circuit also includes resistor R7. One end of resistor R7 is connected to the 01 pin of the optocoupler driver, and the other end of resistor R7 is grounded.

[0047] Specifically, complete electrical isolation between the MCU and MOSFET power output terminals is achieved, improving the reliability and stability of this ignition control drive circuit.

[0048] Optionally, the above-mentioned power supply short-circuit protection circuit includes a resettable fuse F connected to the PMOS transistor. One end of the resettable fuse F is connected to the source of the PMOS transistor, and the other end of the resettable fuse F forms a new DC power input terminal.

[0049] This system provides safety protection in case of MOSFET or igniter failure, preventing accidental firing of the ignition device. The specific circuit connection diagram is shown below. Figure 3 As shown, a 3A / 50V self-resetting fuse is added to the power input terminal. When the MOSFET or external ignition device is abnormally damaged and short-circuited, the current increases to the fuse's breaking current. The fuse will then melt due to overheating, breaking the circuit and preventing accidental firing. When the current electronic devices return to normal, the fuse current returns to normal, and the circuit works normally. This also avoids the safety hazard of accidental firing of the small turbojet engine igniter and prevents the risk of damage to other circuits due to abnormal damage, thus improving the safety of this ignition control drive circuit.

[0050] Optionally, the gate protection circuit includes a resistor R10 connected to the PMOS transistor. One end of the resistor R10 is connected to the gate of the PMOS transistor, and the other end of the resistor R10 is connected to pin 02 of the optocoupler driver. The resistance of the resistor R10 is 10 ohms. The resistor R10 is also connected in parallel with a diode D2. The input of the diode D2 is connected to the gate of the PMOS transistor, and the output of the diode D2 is connected to pin 02 of the optocoupler driver.

[0051] Specifically, if the gate of the power transistor is directly driven, it will cause the driven power transistor to turn on and off rapidly. However, this may cause voltage oscillation between the drain and source of the power transistor, or it may cause the power transistor to suffer excessive di / dt, leading to false turn-on. To avoid the above phenomena, a resistor R10 with a value of 10 ohms is connected in series between the output of the optocoupler driver and the gate of the MOSFET. The diode D2 connected in parallel with this resistor serves to discharge the gate at the falling edge of the pulse, so that the field-effect transistor can be quickly turned off, reducing power consumption. The gate drive signal is as follows: Figure 4 As shown.

[0052] The presence of resistor R10 and diode D2 prevents voltage oscillations between the drain and source of the power transistor and avoids false turn-on caused by excessively high di / dt. This improves the reliability and stability of the ignition control drive circuit.

[0053] Optionally, the above-mentioned Vgs overvoltage protection circuit includes a diode D1 that is connected to the PMOS transistor, and the diode D1 is located between the gate of the PMOS transistor and the resistor R4. The input terminal of the diode D1 is connected to the gate of the PMOS transistor, and the output terminal of the diode D1 is connected to one end of the resistor R4.

[0054] Specifically, a dedicated Vgs overvoltage protection circuit was designed for the ignition control drive circuit of a small turbojet engine to prevent damage to the MOSFET from voltage spikes caused by frequent switching or abnormal conditions in the electronic ignition system. This improves the reliability and stability of the ignition control drive circuit.

[0055] Specifically, because the impedance between the gate and the source is very high, the voltage change between the drain and the source will be coupled to the gate through the inter-electrode capacitance, resulting in a very high gate-source spike voltage. This voltage will cause the very thin gate-source oxide layer to break down. At the same time, the gate is easy to accumulate charge, which will also cause the gate-source oxide layer to break down. Therefore, a Zener diode (D1 in the figure) should be connected in parallel with the gate of the MOSFET to limit the gate voltage to below the Zener diode's voltage value and protect the MOSFET from being broken down.

[0056] Optionally, the above-mentioned Vds overvoltage protection circuit includes diode D3 and RC snubber circuit, with diode D3 connected in parallel with RC snubber circuit. The input terminal of diode D3 is connected to the drain of PMOS transistor, and the output terminal of diode D3 is connected to the source of PMOS transistor.

[0057] Although the drain-source breakdown voltage VDS is generally very high, without drain-source protection circuitry, a sudden change in current during device switching can still cause a drain voltage spike, potentially damaging the MOSFET. The faster the power transistor switches, the higher the overvoltage will be. To prevent device damage, Zener diode clamping (D3 in the diagram) and an RC snubber circuit (C1, R11 in the diagram) are typically used for protection. This prevents the MOSFET from breaking down due to excessively high Vds under abnormal conditions, thus improving the reliability and stability of this ignition control drive circuit.

[0058] Specifically, the MCU control circuit provided in this embodiment is based on an isolated optocoupler drive output circuit, achieving complete electrical isolation between the MCU terminal and the MOSFET power output terminal. This type of control circuit has extremely strong anti-electromagnetic interference capabilities and can also achieve level conversion, as detailed below. Figure 3As shown, when the I / O port outputs a low level, current flows through the LED. The current flowing through the optocoupler is 3.3V / R1 = 11mA, and the optocoupler reaches its rated operating condition, causing the other end of the optocoupler to conduct. After the optocoupler conducts, the current flows from 28V back to GND through R4 and R7. Here, the threshold turn-on voltage of a typical MOSFET is generally between 4.5V and 12V. In this design, R4 and R7 are 20K and 51K respectively. Using Ohm's law, Vgs = 28V / (R4+R7)*R4 = 7.9V, which can safely and reliably turn on the MOSFET. This greatly improves the reliability and stability of this ignition control drive circuit.

[0059] Specifically, in the power supply short-circuit protection circuit provided in this embodiment, since the igniter used in a typical small turbojet engine stores about 3J of energy, its input current is generally about 1.5A, and the voltage is 24V to 30V, this design adds a self-resetting fuse at the DC 28V input terminal, with a rated operating condition of 3A / 50V, which can fully achieve the expected effect.

[0060] Specifically, in this embodiment, in order to prevent the circuit from being damaged or malfunctioning due to excessively high di / dt of the MOSFET, a 10R current-limiting resistor is first added to the gate. At the same time, a bleeder diode is connected in parallel at R10, which enables the MOSFET to be quickly turned off when it is turned off, thereby reducing circuit power consumption and heat generation.

[0061] Specifically, due to the high impedance of the gate and source, the voltage change between the drain and source will be coupled to the gate through the inter-electrode capacitance, resulting in a relatively high gate-source spike voltage. This voltage can cause the very thin gate-source oxide layer to break down. At the same time, the gate can easily accumulate charge, which can also cause the gate-source oxide layer to break down. In this embodiment, a Zener diode (D1 in the figure) is connected in parallel with the gate of the MOS transistor to limit the gate voltage to below the Zener diode's voltage value, thus protecting the MOS transistor from being broken down.

[0062] Specifically, although the drain-source breakdown voltage VDS is generally very large, if there is no protection circuit at the drain and source, a drain voltage spike may still be generated due to the sudden change in current during device switching, which can damage the MOSFET. The faster the switching speed of the power transistor, the higher the overvoltage generated. To prevent device damage, Zener diode clamping is usually used (…). Figure 3 D3) and RC buffer circuit ( Figure 3 The circuit includes C1 and R11 protection measures; this circuit can effectively prevent the MOSFET from malfunctioning due to Gds overvoltage.

[0063] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. An ignition driver circuit for an aero turbine engine, comprising a PMOS transistor, a resistor R4 and a resistor RL, a source of the PMOS transistor forms a DC power input terminal, a gate of the PMOS transistor forms a control signal input terminal, the source and the gate of the PMOS transistor are connected to two ends of the resistor R4 respectively, one end of the resistor RL is connected to a drain of the PMOS transistor, and the other end of the resistor RL is grounded, characterized in that, The MCU control circuit and the ignition power driving circuit connected with the PMOS tube are also included, and the MCU control circuit is connected with the control signal input end; wherein the ignition power driving circuit includes a power short circuit protection circuit, a gate protection circuit, a Vgs overvoltage protection circuit and a Vds overvoltage protection circuit.

2. An aircraft turbojet igniter drive circuit according to claim 1, characterized in that, The MCU control circuit includes an optocoupler driver, a resistor R9 and a resistor R1, wherein: The 02 pin of the optocoupler driver is connected with the control signal input end, the A pin and the K pin of the optocoupler driver are connected with one end of the resistor R1 and one end of the resistor R9 respectively, the other end of the resistor R1 and the other end of the resistor R9 are connected and form a power supply input end; and the K pin of the optocoupler driver forms a new control signal input end.

3. An aircraft turbojet igniter drive circuit according to claim 2, characterized in that, The MCU control circuit further includes a resistor R7, one end of the resistor R7 is connected with the 01 pin of the optocoupler driver, and the other end of the resistor R7 is grounded.

4. An aircraft turbojet igniter drive circuit according to claim 1, wherein, The power short circuit protection circuit includes a self-resetting fuse F connected with the PMOS tube, one end of the self-resetting fuse F is connected with the source of the PMOS tube, and the other end of the self-resetting fuse F forms a new DC power supply input end.

5. An aircraft turbojet igniter drive circuit according to claim 2, characterized in that, The gate protection circuit includes a resistor R10 connected with the PMOS tube, one end of the resistor R10 is connected with the gate of the PMOS tube, and the other end of the resistor R10 is connected with the 02 pin of the optocoupler driver.

6. An aircraft turbojet igniter drive circuit according to claim 5, characterized in that, The resistor R10 has a resistance of 10 ohms.

7. An aircraft turbojet igniter drive circuit according to claim 5, characterized in that, The resistor R10 is further connected with a diode D2, the input end of the diode D2 is connected with the gate of the PMOS tube, and the output end of the diode D2 is connected with the 02 pin of the optocoupler driver.

8. An aircraft turbojet igniter drive circuit according to claim 1, characterized in that, The Vgs overvoltage protection circuit includes a diode D1 connected with the PMOS tube, and the diode D1 is located between the gate of the PMOS tube and a resistor R4, the input end of the diode D1 is connected with the gate of the PMOS tube, and the output end of the diode D1 is connected with one end of the resistor R4.

9. An aircraft turbojet igniter drive circuit according to claim 1, wherein, The Vds overvoltage protection circuit includes a diode D3 and an RC buffer circuit, and the diode D3 is connected with the RC buffer circuit in parallel, the input end of the diode D3 is connected with the drain of the PMOS tube, and the output end of the diode D3 is connected with the source of the PMOS tube.

10. An aircraft turbojet igniter drive circuit according to claim 9, characterized in that, The RC buffer circuit includes a resistor R11 and a capacitor C1 connected with each other, the other end of the resistor R11 is connected with the drain of the PMOS tube, and the other end of the capacitor C1 is connected with the source of the PMOS tube.

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